Clamps used for the detachable attachment or connection of cables, wires or lines to one another or to devices are generally known in electrical engineering. The clamping devices ensure a long-term and secure electrical contact. The electrical contact is achieved by mechanically fixing the attached cables, wires or lines in an electrically conductive body using a screw or spring. Clamping devices can likewise be attached to electrical devices, so that these electrical devices can be electrically contacted using cables or lines.
For example, housings of circuit-breakers, which typically can switch currents from 10 A to 100 A and more, include such clamping devices. Individual phases of the currents are typically switched separately, for example in what is known as a pole housing. Accommodated in the pole housing are a movable contact and a fixed contact, which can be mechanically opened or closed to switch the current off or on respectively. Electrical switches can be designed to switch an individual phase, or else several phases. The individual phases of the currents are managed by means of cables or lines to the housing of the circuit-breaker and are connected there by way of clamping devices.
FIG. 1 shows a clamp 100 typical of the type used. The clamp comprises a base body 110, which is for example bent such that it comprises an opening for receiving a cable or line. According to FIG. 1 the opening has a height T and a width W, and extends along the length L. In FIG. 1 a cable or line with a circular cross-section of circumference U is schematically drawn in, and projects into the opening of the base body 110. A clamping plate 200, which is designed to be height-adjustable, can be moved downward according to the illustration in FIG. 1 and thus presses the cable or line against an electrical contact point 300 of the clamping device 100. The electrical contact point 300 of the clamping device 100 can for example be the terminal lug of a fixed contact of the electrical switch.
Typical clamping devices have the disadvantage that they cannot optimally accommodate cables or lines of different cross-sections and thus do not have a large dynamic range. Typically the clamping plate 200 is designed to be curved on the side facing the cable and this curvature is adjusted to the surface curvature of the cable. Likewise the middle of the clamping plate 200 can be designed to be straight on the side facing the cable with surfaces drawn downward in the edge region of the clamping plate 200 to enclose the cable. If for example a cable with a much smaller cross-section is now to be clamped in such a clamping device there is a risk that the cable cannot be fixed by the height-adjustable clamping plate and slips out of the clamping connection. For this reason different clamping devices have until now been built into circuit-breakers for cables with very different cross-sections.